code: def test_on_zeros(self):
      test_length = self.o.hop_size * 100
      read = 0
      # test on zeros
      vec = aubio.fvec(self.o.hop_size)
      transpose_range = 24
      while read < test_length:
          # transpose the samples
          out = self.o(vec)
          self.assertTrue((out == 0).all())
          # position in the file (between 0. and 1.)
          percent_read = read / float(test_length)
          # variable transpose rate (in semitones)
          transpose = (
              2 * transpose_range * percent_read - transpose_range
          )
          # set transpose rate
          self.o.set_transpose(transpose)
          read += len(vec)
  
file_path: aubio/python/tests/test_pitchshift.py
imports: from numpy.testing import TestCase
  from _tools import parametrize, skipTest
  import numpy
  import aubio
label_desc: Use image node_id 3 for calling the aubio_pitchshift obj's underlying member method code with example usage: obj.test_on_zeros() without return types